30 TULIP. [CH. II 



fitting closely over one another. These are morphologically 

 leaves, and it is for this reason that it bears a different name 

 bulb, because its reserve materials are stored not in a 

 thickened stem but in specially modified swollen leaves. 

 Nevertheless its resemblances to a tuber are more 

 important than its differences, for the swollen scaly leaves 

 are necessarily borne on a stem, so that the bulb only 

 differs from the tuber in the predominant development of 

 leaves, which are insignificant in the last named. 



It is well to begin by examining a bulb growing 

 in the garden during the summer. In the centre is 

 seen the stalk which, during the spring, bore leaves 

 and flower; it can be seen to be continuous with the 

 main axis of the bulb which bears the scales. It should 

 be noted that these scales are no longer plump and 

 fleshy, but dry and withered ; this is because they have 

 yielded their stores to supply material for the development 

 of the flowering stem. Since the bulb is exhausted it is 

 not obvious in what way next year's flowering stalk is to 

 be provided for. In fig. 11 (A) it will be seen that on 

 one side of the flower stalk a new bulb has formed: 

 the leaves on the flowering stem have, during the summer, 

 built up more organic material than the plant needed, 

 and this has been transferred downwards, and has led 

 to the growth (out of a minute bud hidden among 

 the scales) of a new bulb. Next spring this bulb 

 (B, fig. 11) will throw up a leafy and flowering stem, 

 will be in its turn exhausted, and will among its scales 

 give birth to another new bulb. The death of the old 

 bulb going on side by side with the development of a new 



